If the resistor is the load (filters are only meaningful for matched constant resistance source and load), then this is true.

It's kind of dubious to say the phase shift is the reason, but because phase shift and impedance are locked together, this is more-or-less fine:https://en.wikipedia.org/wiki/Minimum_phase..._phase_response(There should be a whole article talking about this matter; it's one of those wave-particle duality things, at its root. Suffice it to say: any time magnitude is changing, phase is necessarily changing at least a certain amount as well. Nonminimum phase networks can have more phase shift, but not less, since less would violate causality. Which puts the limit on how "fast" a filter of some design can be, as must be the case.)

If you imagine a source not as a voltage, but as a power source with some constant output and some reflected amount so that the total comes out right, then when the reactance is small, the source and load are connected together and no power is reflected. When the reactance is large, more power is reflected and less transmitted.

And yes, if you keep your mind active in terms of impedance matching, then you will realize: it's not that a battery sitting on the table is "open circuit", it's that it's constantly transmitting a large amount of power, and all of it is being reflected back from the lack of matching!

Whether this is a useful model of the world depends on what you're doing; normally it's not a concern, but it becomes so much harder to work without it, at RF, or when dealing with any kind of passive circuit (where impedances and ratios, transmission and reflection are the important figures).

Tim

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Answering questions is a tricky subject to practice. Not due to the difficulty of formulating or locating answers, but due to the human inability of asking the right questions; a skill that, were one to possess, would put them in the "answering" category.